1. Field of the Art
The present invention relates to a sol in which surface-modified colloidal particles are dispersed in a liquid, wherein the surface-modified colloidal particles are obtained by using anhydrous zinc antimonate colloidal particles, metal oxides comprising tin atom, zinc atom, antimony atom and oxygen atom, or tin oxide-doped anhydrous zinc antimonate colloidal particles as nuclei, and by coating the surface of the nuclei with an aluminum-containing substance, a polymer type surfactant or both of them. The anhydrous zinc antimonate sol according to the present invention is used for several purposes such as transparent antistatic materials in the form of resin, plastic, glass, paper, magnetic tape or the like, transparent UV absorbers, transparent heat radiation absorbers, high refractive index hard coating agent, anti-reflective agent and the like.
2. Description of the Related Art
There are disclosed aqueous sols or organic solvent sols of anhydrous zinc antimonate. These sols include aqueous sols or organic solvent sols of anhydrous zinc antimonate that are stabilized with alkyl amine such as ethyl amine, propyl amine, isopropyl amine, diisobutyl amine or the like, alkanol amine such as triethanol amine, monoethanol amine or the like, diamine such as ethylene diamine or the like, oxycarboxylic acid such as lactic acid, tartaric acid, malic acid, citric acid or the like. The organic solvents include alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol or the like, glycols such as ethylene glycol, diethylene glycol or the like, cellosolves such as ethyl cellosolve, propyl cellosolve or the like, amides such as dimethyl formamide, dimethyl acetamide or the like (JP-A 6-219743).
In addition, there are also disclosed sols in which surface-modified colloidal particles are dispersed in a liquid, and contain amine and/or oxycarboxylic acid, wherein the surface-modified anhydrous zinc antimonate colloidal particles are obtained by using anhydrous zinc antimonate colloidal particles as nuclei, and by coating the surface of the nuclei with a silicon-containing substance (JP-A11-314918).
The organic solvent sols of anhydrous zinc antimonate and the related materials thereof are used for e.g., transparent antistatic paints or transparent heat radiation absorbing paints by utilizing the characteristics that are fine particles. In this case, paints are obtained by mixing organic solvent sols of anhydrous zinc antimonate and the related materials thereof with several resins. The resulting resins are required that the particles in the anhydrous zinc antimonate sol and the related metal oxide sol are not aggregated but are dispersed in a state close to primary particles. The solvents for resins used for the purpose are hydrophobic solvents such as toluene or xylene, alcohols with a high boiling point such as isopropyl alcohol or butyl alcohol. When the solvents with a law boiling point are present in a paint, the solvents cause whitening of the coating film due to flushing, or the like. Thus, it is generally preferable to replace methanol with the above-mentioned organic solvent. Consequently, hydrophobic solvents such as toluene or xylene or solvents with a high boiling point such as isopropyl alcohol or butyl alcohol are used for the organic solvent sols of anhydrous zinc antimonate used for transparent antistatic paints or transparent heat radiation absorbing paints that are obtained by mixing with several resins.
However, the organic solvent sol of anhydrous zinc antimonate stabilized by adding alkyl amine, alkanol amine, diamine and oxycarboxylic acid that is described in JP-A 6-219743 is deficient in dispersion properties of sol particles in a hydrophobic solvent such as toluene or xylene or a liquid mixed with each resin. Thus, when it is used for transparent antistatic paints or transparent heat radiation absorbing paints, it is required to improve further transparency.